Other topics discussed during the two-day Association of Southeast Asian Nations summit included Myanmar's bid to take over the rotating chair of the regional grouping in 2014 - though a final decision has yet to be made - and concerns about food shortages, spiraling energy prices, human trafficking and maritime security.

They focused heavily on the potentially oil-rich Spratly islands, claimed in whole or in part by China and four ASEAN members - Malaysia, the Philippines, Brunei and Vietnam.

The smaller nations, together with the U.S., worry that China may use its military might to seize the area outright or assume de facto control with naval patrols.

That could threaten one of the world's busiest commercial sea lanes.

"We deemed the South China Sea issue, in all its various dimensions, as having the potential to undermine the stability of our region," according to the final communique released after the meeting.

The annual summit was supposed to focus on developing an integrated regional economic zone by 2015, but repeated outbreaks of fighting along the Thai-Cambodia border stole the show.

Host Indonesian President Susilo Bambang Yudhoyono said in his opening statement that little can be accomplished without peace and stability among member countries.

To that end, he agreed to mediate the talks between the Cambodian and Thai prime ministers about fighting that has killed 20 people in the last two weeks and sent tens of thousands fleeing.

The deadly spat - focused around ancient temples claimed by the two nations - has stirred nationalist sentiment on both sides.

But analysts say domestic politics is fanning the fire, especially in Thailand, where the military that staged a coup in 2006 could be posturing ahead of elections expected as early as next month.

Neither side appeared ready to budge, however.

During the plenary session on Saturday, Cambodian Prime Minister Hun Sen called a demand by Thailand to withdraw troops from the area before it allows for the deployment of outside military observers both "irrational and unacceptable."

"It's Thailand that has to withdraw its troops from the vicinity," he said, reiterating his position to reporters following Sunday's three-way talks.

Thai Prime Minister Abhisit Vejjajiva stressed, again, that the disagreement should be settled bilaterally, not on the international stage, as apparently favored by Cambodia.

"The ultimate objective must be to achieve lasting peace," not to score "political points," he said.

Talks will continue between foreign ministers from Thailand, Cambodia and Indonesia on Monday afternoon.

Meanwhile, Southeast Asian leaders said while they agreed in principal to the idea of Myanmar taking over the rotating chair of ASEAN in 2014, the final decision, expected later this year, should be contingent on continued democratic reforms.

That represented a marked shift from a draft statement that had been circulating hours earlier saying member nations had "consented" to the proposal by Myanmar's president, Thein Sein, who heads the military-backed party that overwhelmingly won general elections late last year.

The regional grouping chairmanship is supposed to rotate annually among its 10 member countries.

Myanmar, which has more than 2,000 political prisoners, was forced to skip its turn in 2005 after heavy pressure from the international community over slow progress on human rights and other issues.